1. Field of the Invention
The instant disclosure relates to a wafer; in particular, to a wafer formed by slicing an ingot.
2. Description of Related Art
Information products and appliances utilized in daily life such as cell phones, computer motherboards, micro-processors, memory devices, digital cameras, personal digital assistants (PDA), etc., use integrated circuits (IC). Generally speaking, integrated circuits refer to the use of wafers undergone different semiconductor fabrication processes in creating various individual circuit elements.
The semiconductor fabrication process involves crystallization (ingot forming), surface grinding, slicing, polishing, and cleaning. When the ingot is sliced to form wafers, the slicing process determines how many wafers and chips that can be made in subsequent processes. Therefore, an improvement in the slicing process of the ingot can greatly impact the production capability of the semiconductor industry.
The manufacturing process of silicon wafers typically begins having the ingot undergoing a machining process such as surface grinding followed by slicing. However, for an ingot that is more brittle, the machining process may lead to excessive scraps. Namely, the cutting tools can cause surface cracks for the ingot and form microscopic cracks around the periphery of the wafers. These wafers are more likely to break or crack during subsequent refining processes, resulting lower yield rate.
Additionally, individual wafers are subjected to various external forces during the different refining processes. When these external forces exceed the maximum strength of the wafer or are over-concentrated on the wafer, the wafer may crack or break resulting in a poor yield rate.